JP2018103170A - Membrane module operation method and membrane module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of operating a membrane module capable of sufficiently discharging sediments and greatly reducing the amount of sediment remaining in the upper primary side chamber.SOLUTION: Provided is an operational method of a membrane module 1, in which a membrane element 3 made of a porous body is housed in a casing 2, the membrane element 3 has a plurality of through flow passages 11 penetrating from one end to the other end and having an inner peripheral surface as a primary side, the through flow passage 11 is disposed in the casing 2 so as to be provided in the vertical direction, an upper primary chamber 16 which exposes the upper end portion of the membrane element 3 and communicates with the through flow path 11 is formed in the upper portion of the casing 2, and treated water is obtained by filtering raw water at the membrane element 3. The method includes a sediment discharge step for supplying a fluid W1 into the upper primary chamber 16 to discharge a deposit 40 in the upper primary chamber 16 together with the fluid W1 to the outside.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a method of operating a membrane module and a membrane module that obtain treated water by filtering raw water through a membrane element made of a columnar porous body.

  Conventionally, as this type of membrane module, for example, as shown in FIG. 15, there is one in which a cylindrical cell structure 111 made of a porous body is accommodated in a housing 112. The cell structure 111 has a plurality of cells 113 penetrating from one end to the other end, and is provided in the housing 112 so that the cells 113 are in the vertical direction.

  The housing 112 includes a raw water inflow path 115 for allowing the raw water 114 to flow into the lower portion thereof. Further, a side surface portion of the housing 112 is provided with a treated water outflow path 117 for flowing out treated water 116 (filtered water) obtained by filtering the raw water 114 with the cell structure 111.

  The housing 112 has a cap portion 118 at the upper end. A predetermined space 119 is formed in the cap portion 118, and a pressurized gas inflow path 120 through which the pressurized gas 123 flows into the predetermined space 119 is connected to the upper surface of the cap portion 118.

  According to this, among the raw water 114 that flows in from the raw water inflow path 115, most of the raw water 114 that flows into the cell 113 located at the center of the cell structure 111 passes through the cell 113 and caps as the raw water 114 with high pressure. It flows into a predetermined space 119 in the portion 118. Moreover, what has flowed into the cell 113 located one outside (outer peripheral side) from the center of the cell structure 111 passes through the cell 113 as a small amount of raw water 114 at a lower pressure than the raw water 114 and passes through the cell 113. Into the predetermined space 119.

  Of the raw water 114, the amount of the raw water 114 that flows into the cell 113 closest to the outer periphery of the cell structure 111 (the outermost cell 113) is substantially the total amount as raw water 114 (treated water 116 after passing through the cell structure 111). It passes through the outer periphery of the cell structure 111.

  As described above, when substantially the entire amount of the raw water 114 permeates the outer peripheral portion of the cell structure 111, the water pressure applied to the predetermined space 119 side from the end portion on the cap portion 118 side of the outermost peripheral cell 113 is very low. Therefore, the raw water 114 flowing into the predetermined space 119 flows back as raw water 114 from the outermost peripheral cell 113, passes through the outer peripheral portion of the cell structure 111, and is taken out from the treated water outflow path 117 as treated water 116. It is. In addition, the flow of said raw | natural water has shown the case where the water permeability is so large that the cell 113 located in the outer peripheral side of the cell structure 111 is shown. In FIG. 15, each arrow schematically shows the flow of raw water 114 and treated water 116.

  According to such a filtration method, a part of the foreign matter in the raw water accumulates in the predetermined space 119 in the cap portion 118, and the amount of foreign matter collected by the cell structure 111 per unit time is reduced. If attention is paid only to the cell 113, it becomes possible to stably operate continuously for a long time.

  Further, by filtering the raw water 114 using the membrane module as described above, a part of the foreign matter in the raw water 114 is accumulated in the predetermined space 119 in the cap part 118, and the accumulated foreign matter is separated from the deposit 121. It accumulates in the cap part 118. For this reason, after filtering the raw water 114, the following backflow cleaning is performed to perform an operation for discharging the deposit 121 in the cap portion 118 to the outside.

  That is, as shown in FIG. 16, pressurized treated water 116 (filtrated water) is caused to flow from the treated water outflow path 117 into the housing 112, and the pressurized gas 123 is allowed to flow from the pressurized gas inflow path 120 to a predetermined space. 119 is supplied to flow into the cell 113. Thereby, the treated water 116 passes through the cell 113 from the top to the bottom together with the small one of the deposits 121 in the cap part 118 and is discharged to the raw water inflow path 115.

  The membrane module as described above is described in, for example, Patent Document 1 below.

Japanese Patent No. 4195824

  However, in the above-described conventional type, if the deposit 121 in the cap portion 118 has a size equal to or larger than the inner diameter of the cell 113 in the backflow cleaning shown in FIG. 16, the deposit 121 is sufficiently removed from the cap portion 118. It is difficult to discharge, and even if backwashing is performed, the deposit 121 accumulates in the cap portion 118 or the cell 113, hindering backwashing and causing a decrease in filtration performance. is there.

  Further, such a problem occurs without being limited to the case where the water permeability of each cell 113 is positively changed as in Patent Document 1 described above. That is, in all the cells 113 of the cell structure 111, it is difficult to equalize the filtration performance and the cleaning performance, and the performance is slightly different between the cells 113, and as a result, the deposit 121 is obtained. Is accumulated in the cap portion 118.

  An object of the present invention is to provide a method for operating a membrane module and a membrane module capable of sufficiently discharging the deposit and greatly reducing the amount of the deposit remaining in the upper primary chamber.

In order to achieve the above object, according to the first aspect of the present invention, a membrane element made of a columnar porous body is housed in a casing,
The membrane element has a plurality of through-flow passages penetrating from one end to the other end and having the inner peripheral surface as the primary side, and is provided in the casing so that the through-flow passage is in the vertical direction.
In the upper part of the casing, an upper primary side chamber is formed which is exposed to the upper end portion of the membrane element and communicates with the through flow path.
A membrane module operating method for obtaining treated water by filtering raw water through a membrane element,
A deposit discharging step of supplying a fluid into the upper primary chamber and discharging deposits in the upper primary chamber together with the fluid to the outside is provided.

  According to this, in the membrane filtration step, raw water is supplied from the primary side of the membrane module to the lower side of the membrane element, and permeates the membrane element from the primary side to the secondary side while flowing through the through flow path from the lower side to the secondary side. Water is taken out from the secondary side of the membrane module. At this time, a part of the foreign matter in the raw water accumulates in the upper primary side chamber, and the accumulated foreign matter becomes a deposit and accumulates in the upper primary side chamber.

  Thereafter, in the deposit discharging step, the fluid is supplied into the upper primary chamber, and the deposit in the upper primary chamber is discharged to the outside together with the fluid. As a result, even if the deposit in the upper primary chamber does not pass through the through-flow passage having a large passage resistance from the top to the bottom, the deposit is surely and sufficiently discharged to the outside of the membrane module to enter the upper primary chamber. The amount of deposits remaining can be greatly reduced.

  The operation method of the membrane module in the second invention is to discharge the deposit in the upper primary side chamber to the outside without passing through the through channel of the membrane element in the deposit discharging step.

  According to this, in the deposit discharging step, the fluid is supplied into the upper primary chamber, and the deposit in the upper primary chamber is discharged outside without passing through the through channel of the membrane element. As a result, even if the deposit in the upper primary side chamber does not pass through the narrow through-flow passage having a large passage resistance from top to bottom, the deposit is surely and sufficiently discharged to the outside of the membrane module, The amount of deposits remaining in the side chamber can be greatly reduced.

  In the operation method of the membrane module in the third invention, in the deposit discharging step, the fluid is supplied from the secondary side of the membrane module to the upper primary side chamber through the through passage of the membrane element.

  According to this, in the deposit discharging step, the fluid is supplied from the secondary side of the membrane module to the upper primary side chamber through the through passage of the membrane element, and the deposit in the upper primary side chamber is discharged to the outside together with the fluid. The

In the operation method of the membrane module according to the fourth aspect of the present invention, a lower primary side chamber communicating with the through channel is formed at the lower portion of the casing, with the lower end portion of the membrane element exposed.
In the deposit discharging step, the fluid is supplied from the lower primary side chamber to the upper primary side chamber through the through passage of the membrane element.

  According to this, in the deposit discharging step, the fluid is supplied from the lower primary side chamber to the upper primary side chamber through the through passage of the membrane element, and the deposit in the upper primary side chamber is discharged to the outside together with the fluid.

In the operation method of the membrane module according to the fifth aspect of the invention, a lower primary side chamber communicating with the through channel is formed at the lower portion of the casing, with the lower end portion of the membrane element exposed.
Having a membrane filtration step and a back pressure washing step,
In the membrane filtration step, raw water is supplied to the lower primary side chamber, permeates from the primary side to the secondary side of the membrane module by the dead end filtration method, and is taken out from the secondary side of the membrane module as treated water,
In the back pressure washing process, the back washing fluid is supplied to the membrane element from the secondary side of the membrane module, passes through the membrane element, and is discharged from the lower primary side chamber to the outside through the through channel. .

  According to this, in a membrane filtration process, raw | natural water is filtered with a membrane element and taken out as treated water.

  Further, in the back pressure washing process, the back washing fluid is supplied to the membrane element from the secondary side, permeates the membrane element, flows from the top to the bottom through the through channel, and is discharged from the lower primary side chamber to the outside. The As a result, the foreign matter adhering to the inside of the through channel is peeled off by the flow of the backwashing fluid and is discharged together with the backwashing fluid from the lower primary side chamber to the outside, so that the membrane element is backwashed.

  The operation method of the membrane module according to the sixth aspect of the invention is that the membrane filtration step and the back pressure washing step are alternately repeated, and when a predetermined time has elapsed, when the number of both steps reaches a predetermined number, In any case where the parameter reaches a predetermined value, the deposit discharging step is performed.

  According to this, as the membrane filtration process and the counter pressure cleaning process are alternately repeated, the amount of deposits in the upper primary chamber gradually increases, so that it becomes difficult to uniformly clean all the through channels, and the counter pressure The membrane differential pressure as the membrane module immediately after the cleaning process gradually increases.

  On the other hand, the deposit discharging process is performed when the predetermined time has elapsed, the number of times of the both processes reaches the predetermined number, or the predetermined operation parameter reaches the predetermined value. Thus, the deposit in the upper primary side chamber is discharged to the outside. For this reason, when the membrane filtration step and the back pressure washing step are alternately repeated after the deposit discharge step, the membrane differential pressure as the membrane module immediately after the back pressure washing step is lowered, thereby improving the filtration efficiency. Kept.

In the operation method of the membrane module in the seventh invention, all or part of the deposit discharging step is performed overlapping with the back pressure cleaning step,
When the deposit discharge process is performed overlapping with the back pressure cleaning process, the backwash fluid that has passed through the membrane element from the secondary side of the membrane module is discharged to the outside from the upper primary chamber and the lower primary chamber. Is.

  According to this, during the back pressure washing process, the gas that was dissolved in the back washing fluid due to the pressure drop that occurs when the back washing fluid passes from the secondary side to the primary side of the membrane element. Components may gasify and collect and stay on the surface of the membrane element or in the upper primary chamber. On the other hand, by performing all or part of the deposit discharging process overlapping with the back pressure cleaning process, when these both processes are performed overlappingly, the membrane element is removed from the secondary side of the membrane module. Since the permeated backwash fluid is discharged from the upper primary side chamber and the lower primary side chamber to the outside, the deposit and gas in the upper primary side chamber are discharged from the upper primary chamber together with the backwash fluid. Thereby, the time required to extract the gas staying in the upper primary side chamber can be shortened.

The membrane module in the eighth invention is a membrane module that obtains treated water by filtering raw water through a membrane element,
A membrane element made of a columnar porous body is housed in a casing,
The membrane element has a plurality of through-flow passages penetrating from one end to the other end and having the inner peripheral surface as the primary side, and is provided in the casing so that the through-flow passage is in the vertical direction.
In the upper part of the casing, an upper primary side chamber is formed which is exposed to the upper end portion of the membrane element and communicates with the through flow path.
On the side surface of the upper primary side chamber, a discharge opening for discharging the deposit together with the fluid to the outside of the upper primary side chamber is provided.

  According to this, in the deposit discharging step, the fluid is supplied into the upper primary chamber, and the deposit in the upper primary chamber is discharged to the outside together with the fluid from the discharge opening provided on the side surface of the upper primary chamber. As a result, even in the case of a large sediment having a high sedimentation property, the sediment in the upper primary chamber does not pass through the through flow passage having a large passage resistance from the top to the bottom, and the deposit is surely and sufficiently obtained. The amount of sediment remaining in the upper primary chamber can be greatly reduced.

The membrane module in the ninth invention is a membrane module that obtains treated water by filtering raw water with a membrane element,
A membrane element made of a columnar porous body is housed in a casing,
The membrane element has a plurality of through-flow passages penetrating from one end to the other end and having the inner peripheral surface as the primary side, and is provided in the casing so that the through-flow passage is in the vertical direction.
In the upper part of the casing, an upper primary side chamber is formed which is exposed to the upper end portion of the membrane element and communicates with the through flow path.
A supply opening for supplying a fluid for discharging deposits into the upper primary chamber is provided on a side surface of the upper primary chamber.

  According to this, since the supply opening is provided on the side surface of the upper primary side chamber, when the fluid flows into the upper primary side chamber from the supply opening, the deposit in the upper primary side chamber receives the fluid from the side. As a result, the deposit is easily peeled off from the end of the membrane element.

  Thereby, even if it is a deposit with strong adhesiveness, it can discharge | emit to the exterior of a membrane module reliably and fully, and the quantity of the deposit which remains in an upper primary side chamber can be reduced significantly.

  As described above, according to the present invention, deposits can be sufficiently discharged, and the amount of deposits remaining in the upper primary chamber can be greatly reduced.

It is sectional drawing of the membrane module in the 1st Embodiment of this invention. FIG. 3 is an XX arrow view in FIG. 2. It is sectional drawing which shows the membrane filtration process of the operating method of a membrane module. It is sectional drawing which shows the back pressure washing | cleaning process of the operating method of a membrane module. It is sectional drawing which shows the deposit discharge process of the operating method of a membrane module. It is a timetable of each process of the operating method of a membrane module. It is a graph which shows the relationship between the operation time of a membrane module, and a membrane differential pressure. It is sectional drawing which shows the deposit discharge process of the operating method of the membrane module in the 2nd Embodiment of this invention. It is sectional drawing which shows the deposit discharge process of the operating method of the membrane module in the 3rd Embodiment of this invention. It is sectional drawing which shows the deposit discharge process of the operating method of the membrane module in the 4th Embodiment of this invention. It is sectional drawing which shows the deposit discharge process of the operating method of the membrane module in the 5th Embodiment of this invention. It is a timetable of each process of the operating method of the membrane module in the 6th Embodiment of this invention. It is sectional drawing when the deposit discharge process of the operating method of a membrane module is performed overlapping with a back pressure washing process. It is a timetable of each process of the operating method of the membrane module in the 7th Embodiment of this invention. It is sectional drawing of the conventional membrane module. It is sectional drawing which shows backflow washing | cleaning of a membrane module same as the above.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(First embodiment)
In 1st Embodiment, as shown in FIG. 1, FIG. 2, 1 is a membrane module used for a water purification process etc., for example. The membrane module 1 has a casing 2 and a membrane element 3 accommodated in the casing 2. The casing 2 has a cylindrical body part 6, an upper cap 7 that is detachably attached to the upper end of the body part 6, and a lower cap 8 that is detachably attached to the lower end of the body part 6. .

  The membrane element 3 is made of a cylindrical porous body, and has a plurality of through channels 11 that penetrate from one end surface to the other end surface and have a separation membrane layer formed on the inner peripheral surface. It is provided in the casing 2 so that In addition, the through-flow channel 11 has the inner peripheral surface as the primary side.

  Between the outer periphery of the upper end portion of the membrane element 3 and the casing 2 is sealed over the entire periphery by an annular upper seal member 13, and between the outer periphery of the lower end portion of the membrane element 3 and the casing 2 is provided with an annular lower seal member 14. Sealed all around.

  In the upper portion of the casing 2, that is, in the upper cap 7, an upper primary side chamber 16 that exposes the upper end portion of the membrane element 3 and communicates with the through channel 11 is formed. On the upper surface of the upper cap 7, a pressurized gas inlet 27 through which a pressurized gas G 1 (for example, pressurized air) flows into the upper primary side chamber 16 is formed. A pressurized gas supply pipe 28 and a deposit discharge pipe 30 for discharging the deposit 40 in the upper primary side chamber 16 are branched and connected to the pressurized gas inlet 27.

  In addition, a lower primary side chamber 17 that exposes the lower end portion of the membrane element 3 and communicates with the through flow path 11 is formed in the lower portion of the casing 2, that is, in the lower cap 8. A raw water inlet 19 is formed on the lower surface of the lower cap 8. A raw water supply pipe 20 and a backwash water discharge pipe 21 for discharging backwash water W1 (an example of a backwash fluid) are branched and connected to the raw water inlet 19.

  The body portion 6 of the casing 2 is formed with a treated water outlet 23 for discharging treated water W3 (filtered water) obtained by filtering the raw water W2 with the membrane element 3. A treated water discharge line 24 and a backwash water supply line 25 that supplies the backwash water W1 are branched and connected to the treated water outlet 23.

  The raw water supply pipe 20, the backwash water discharge pipe 21, the treated water discharge pipe 24, the backwash water supply pipe 25, the pressurized gas supply pipe 28, and the sediment discharge pipe 30 are first to first. Six valves 31 to 36 are provided.

  Hereinafter, the operation method of the membrane module 1 will be described.

  As shown in FIG. 6, the operation method of the membrane module 1 includes (1) a membrane filtration step 45, (2) a back pressure cleaning step 46, and (3) a deposit discharge step 47.

  (1) In the membrane filtration step 45, as shown in FIG. 3, the first and third valves 31, 33 are opened, the other valves 32, 34 to 36 are closed, and the raw water W2 in the raw water supply pipeline 20 is closed. Is supplied from the raw water inlet 19 to the lower primary side chamber 17. As a result, the raw water W2 in the lower primary side chamber 17 permeates the membrane element 3 from the primary side to the secondary side in a dead-end filtration manner while flowing through the through flow path 11 from the bottom to the treated water outlet as treated water W3. 23 flows out of the treated water discharge pipe 24 and is taken out to the outside.

  (2) In the back pressure washing step 46, as shown in FIG. 4, the second and fourth valves 32, 34 are opened, the other valves 31, 33, 35, 36 are closed, and the backwash water supply line is closed. The backwash water W <b> 1 in 25 is supplied to the membrane element 3 from the treated water outlet 23. Thereby, the backwash water W1 permeates from the outer periphery (secondary side) of the membrane element 3 to the inner side (primary side), flows from the top to the bottom through the through passage 11 and flows into the lower primary side chamber 17, and the raw water flow It is discharged from the inlet 19 to the outside through the backwash water discharge pipe 21 as backwash drainage.

  Thereby, the foreign matter adhering to the inside of the through channel 11 is separated by the flow of the backwash water W1, passes through the raw water inlet 19 from the lower primary side chamber 17 together with the backwash water W1, and is discharged as backwash water as backwash water. The membrane element 3 is discharged to the conduit 21 and subjected to back pressure cleaning.

  Thereafter, the fifth valve 35 is further opened as a flushing process which is a part of the back pressure cleaning process 46. Thus, the pressurized gas G1 in the pressurized gas supply line 28 is supplied from the pressurized gas inlet 27 into the upper primary chamber 16 while supplying the backwash water W1, and therefore remains in the casing 2. The backwashing water W1 that has been removed together with the separated foreign matter is surely discharged from the raw water inlet 19 through the backwashing water discharge pipe 21 by the pressurized gas G1.

  In the flushing step, the fifth valve 35 is opened while the fourth valve 34 is opened and the backwash water W1 is supplied to the membrane element 3, but the fourth valve 34 is closed. In this state, the fifth valve 35 may be opened.

  (3) In the deposit discharge step 47, as shown in FIG. 5, the fourth and sixth valves 34 and 36 are opened, the other valves 31 to 33 and 35 are closed, and the inside of the backwash water supply pipe 25 Is supplied to the membrane element 3 from the treated water outlet 23 (secondary side of the membrane module 1). As a result, the backwash water W1 permeates from the outer periphery of the membrane element 3 to the inside, flows upward through the through passage 11 and flows into the upper primary side chamber 16, and pressurizes together with the deposit 40 in the upper primary side chamber 16. The gas is discharged from the gas inlet 27 through the sediment discharge pipe 30 to the outside.

  Thereby, even if the deposit 40 in the upper primary side chamber 16 does not pass through the narrow through-passage 11 having a large passage resistance from the top to the bottom, the deposit 40 together with the backwash water W1 is pressurized gas inlet 27. Therefore, the amount of deposit 40 remaining in the upper primary chamber 16 can be significantly reduced by reliably and sufficiently discharging the membrane module 1 to the outside.

  In addition, when performing the above-mentioned back pressure washing process (refer to Drawing 4), backwashing water W1 by the pressure drop accompanying passing from the perimeter (secondary side) to the inside (primary side) of membrane element 3, The gas component dissolved in the backwash water W <b> 1 may be gasified and collected and retained on the surface of the membrane element 3 or the upper primary side chamber 16. On the other hand, backwash water W1 is supplied from the treated water outlet 23 into the upper primary chamber 16 through the through-flow passage 11 of the membrane element 3 by performing the deposit discharging step (see FIG. 5). As a result, the deposit 40 and the gas in the upper primary side chamber 16 are discharged together with the backwash water W1 from the pressurized gas inlet 27 through the deposit discharge pipe 30 to the outside. It is possible to shorten the time required to extract the gas retained in the gas.

  In the operation method of the membrane module 1 as described above, the membrane filtration step (see FIG. 3) and the back pressure cleaning step (see FIG. 4) are alternately repeated. After that, the membrane filtration step and the back pressure washing step may be repeated alternately. At this time, the predetermined time may be set to about one week (that is, 168 hours), for example.

  According to this, as the membrane filtration step and the back pressure cleaning step are alternately repeated, the amount of deposit 40 in the upper primary side chamber gradually increases, so the membrane differential pressure immediately after the back pressure cleaning step gradually increases. Go.

  On the other hand, when the predetermined time has elapsed, the deposit 40 in the upper primary side chamber 16 is discharged to the outside by performing the deposit discharging step. For this reason, after the deposit discharging step, all the through-flow passages 11 of the membrane element 3 can be evenly cleaned, and when the membrane filtration step and the counter pressure cleaning step are repeated again and again, the counter pressure cleaning step Immediately after the membrane differential pressure is lowered, the filtration efficiency is kept good.

  In addition, the membrane filtration step and the back pressure washing step are alternately repeated, and when the number of times of both the above steps (that is, the membrane filtration step and the back pressure washing step) reaches a predetermined number, the deposit discharging step is performed, and then again. Alternatively, the membrane filtration step and the back pressure washing step may be repeated alternately. In this case, as the predetermined number of times, for example, the membrane filtration step and the back pressure washing step may be set to about 10 times.

  According to this, when the predetermined number of times is reached, the deposit 40 in the upper primary side chamber 16 is discharged to the outside by performing the deposit discharging step. For this reason, after the deposit discharging step, all the through-flow passages 11 of the membrane element 3 can be evenly cleaned, and when the membrane filtration step and the counter pressure cleaning step are repeated again and again, the counter pressure cleaning step Immediately after the membrane differential pressure is lowered, the filtration efficiency is kept good.

  Alternatively, the membrane filtration step and the back pressure washing step are alternately repeated, and when a predetermined operating parameter reaches a predetermined value, the deposit discharging step is performed, and then the membrane filtration step and the back pressure washing step are alternately repeated. You may continue to repeat. At this time, as a predetermined operating parameter, for example, the film differential pressure immediately after performing the back pressure cleaning process is used as an index. When this film differential pressure increases and reaches a predetermined value, the deposit discharge process is performed. Also good.

  According to this, when a predetermined operating parameter (film differential pressure) increases and reaches a predetermined value, the deposit 40 in the upper primary chamber 16 is discharged to the outside by performing the deposit discharging step. For this reason, after the deposit discharging step, all the through-flow passages 11 of the membrane element 3 can be evenly cleaned, and when the membrane filtration step and the counter pressure cleaning step are repeated again and again, the counter pressure cleaning step The membrane differential pressure immediately after the straightening is lowered, and thus the filtration efficiency is kept good.

  In addition, as described above, the membrane differential pressure immediately after the back pressure cleaning step is used as an index as the predetermined operating parameter, but the membrane differential pressure just before the back pressure cleaning step may be used as an index.

  Moreover, the graph A of FIG. 7 shows the relationship between the operation time (days) of the membrane module 1 and the membrane differential pressure, and the graph B is an enlarged portion of the graph A. According to the graph A and the graph B, when performing the membrane filtration step 45, the membrane differential pressure gradually increases as the operation time elapses, and then the back pressure washing step 46 is performed, whereby the membrane differential pressure is reduced. Go down once. Thereafter, by performing the membrane filtration step 45 again, the membrane differential pressure gradually increases as the operating time elapses, and then, by performing the back pressure washing step 46 again, the membrane differential pressure once decreases. In this way, by alternately repeating the membrane filtration step 45 and the counter pressure cleaning step 46, the membrane differential pressure P immediately after the counter pressure cleaning step 46 is gradually increased as indicated by the straight line C.

For example, when the film differential pressure P increases and reaches a predetermined value E, the deposit 40 in the upper primary chamber 16 is discharged to the outside of the membrane module 1 by performing the deposit discharging step 47. For this reason, when the membrane filtration step 45 and the back pressure cleaning step 46 are alternately repeated after the deposit discharge step 47, as shown by the straight line D, the membrane difference immediately after the back pressure cleaning step 46 is performed. The pressure P gradually decreases, and thereby the filtration efficiency is restored to a good state.
(Second Embodiment)
In the first embodiment described above, as shown in FIG. 5, in the deposit discharging step, the deposit 40 in the upper primary chamber 16 is discharged as an example of the fluid using the backwash water W1. However, in the second embodiment described below, as shown in FIG. 8, the deposit 40 in the upper primary chamber 16 is discharged using raw water W2 as an example of a fluid.

  That is, in the sediment discharging step, the first and sixth valves 31 and 36 are opened, the other valves 32 to 35 are closed, and the raw water W2 in the raw water supply pipe 20 is fed from the raw water inlet 19 to the lower primary side chamber 17. To supply. Thereby, the raw water W2 in the lower primary side chamber 17 flows from the bottom through the through flow path 11 of the membrane element 3 to the upper primary side chamber 16, and together with the deposit 40 in the upper primary side chamber 16, the pressurized gas inlet 27 is discharged to the outside through the sediment discharge pipe 30.

This ensures that the deposit 40 in the upper primary side chamber 16 can be passed from the pressurized gas inlet 27 together with the raw water W2 even if the deposit 40 does not pass through the narrow through-flow passage 11 having a large passage resistance from top to bottom. In addition, the amount of the deposit 40 remaining in the upper primary side chamber 16 can be greatly reduced by sufficiently discharging the membrane module 1 to the outside.
(Third embodiment)
In the second embodiment described above, as shown in FIG. 8, the deposit 40 in the upper primary side chamber 16 is discharged using raw water W2 as an example of the fluid in the deposit discharging step. In the third embodiment described below, as shown in FIG. 9, the deposit 40 in the upper primary side chamber 16 is discharged as an example of the fluid using the cleaning water W4.

  That is, on the side surface of the lower cap 8, a cleaning water supply port 51 for supplying the cleaning water W <b> 4 into the lower primary side chamber 17 is formed, and the cleaning water supply pipe 52 is connected to the cleaning water supply port 51. Note that a seventh valve 37 is provided in the cleaning water supply conduit 52.

  According to this, in the deposit discharging step, the sixth and seventh valves 36 and 37 are opened, the other valves 31 to 35 are closed, and the cleaning water W4 in the cleaning water supply pipe 52 is supplied to the cleaning water supply port 51. To the lower primary side chamber 17. As a result, the cleaning water W4 in the lower primary side chamber 17 flows from the bottom through the through channel 11 of the membrane element 3 into the upper primary side chamber 16, and flows into the upper primary side chamber 16 together with the deposit 40 in the upper primary side chamber 16. It is discharged from the inlet 27 through the deposit discharge pipe 30 to the outside.

  Thereby, even if the deposit 40 in the upper primary side chamber 16 does not pass through the narrow through-flow passage 11 having a large passage resistance from the top to the bottom, the deposit 40 can be removed from the pressurized gas inlet 27 together with the cleaning water W4. The amount of deposit 40 remaining in the upper primary chamber 16 can be significantly reduced by reliably and sufficiently discharging the membrane module 1 to the outside.

Further, after supplying the cleaning water W4 from the cleaning water supply port 51 to the lower primary side chamber 17 as described above, a pressurized gas G2 (an example of fluid) such as pressurized air is supplied from the cleaning water supply port 51 to the lower primary side chamber. 17 may be injected. As a result, the pressurized gas G2 flows through the through channel 11 of the membrane element 3 and flows into the upper primary side chamber 16, and is discharged from the pressurized gas inlet 27 through the deposit discharge conduit 30 to the outside. For this reason, even if the cleaning water W4 and the deposit 40 remain in the upper primary side chamber 16, the remaining cleaning water W4 and the deposit 40 together with the pressurized gas G2 from the pressurized gas inlet 27 to the deposit discharge conduit. It is reliably discharged outside through 30.
(Fourth embodiment)
The fourth embodiment is a modification of the first embodiment. As shown in FIG. 10, the deposit 40 is placed on the side surface of the upper primary side chamber 16, that is, the side surface of the upper cap 7. A discharge opening 56 for discharging to the outside of the upper primary side chamber 16 is provided together with an example of the fluid. A deposit discharge pipe 30 is connected to the discharge opening 56, and a sixth valve 36 is provided in the deposit discharge pipe 30.

  Hereinafter, the operation method of the membrane module 1 will be described.

  In the deposit discharging step, the fourth and sixth valves 34 and 36 are opened, the other valves 31 to 33 and 35 are closed, and the backwash water W1 in the backwash water supply pipe 25 is treated as the treated water outlet 23 ( The membrane element 3 is supplied from the secondary side of the membrane module 1. Thereby, the backwash water W1 permeates from the outer periphery of the membrane element 3 to the inside, flows upward through the through flow path 11 and flows into the upper primary side chamber 16, and together with the deposit 40 in the upper primary side chamber 16, discharge opening The portion 56 is discharged to the outside through the sediment discharge pipe 30.

  This ensures that the deposit 40 in the upper primary chamber 16 does not pass through the narrow through-passage 11 having a large passage resistance from the top to the bottom together with the backwash water W1 from the discharge opening 56. In addition, the amount of the deposit 40 remaining in the upper primary side chamber 16 can be greatly reduced by sufficiently discharging the membrane module 1 to the outside.

In the fourth embodiment, as in the first embodiment, the deposit 40 in the upper primary side chamber 16 is discharged from the discharge opening 56 to the outside using the backwash water W1. For example, as in the second embodiment (see FIG. 8), the deposit 40 in the upper primary side chamber 16 is discharged from the discharge opening 56 to the outside using the raw water W2. Also good. Alternatively, as in the third embodiment (see FIG. 9), the deposit 40 in the upper primary chamber 16 may be discharged from the discharge opening 56 to the outside using the cleaning water W4.
(Fifth embodiment)
In the fifth embodiment, as shown in FIG. 11, cleaning water W4 (an example of a fluid) for discharging the deposit 40 is applied to the side surface of the upper primary side chamber 16, that is, the side surface of the upper cap 7. There are provided a supply opening 60 for supplying inside and a discharge opening 61 for discharging the deposit 40 to the outside of the upper primary side chamber 16 together with the cleaning water W4.

  In addition, a cleaning water supply pipe 52 is connected to the supply opening 60, and a seventh valve 37 is provided in the cleaning water supply pipe 52. Further, the deposit discharge pipe 30 is connected to the discharge opening 61, and the sixth valve 36 is provided in the deposit discharge pipe 30.

  Hereinafter, the operation method of the membrane module 1 will be described.

  In the deposit discharging step, the cleaning water W4 in the cleaning water supply pipe 52 is discharged from the supply opening 60 by opening the sixth and seventh valves 36 and 37 and closing the other valves 31 to 35. It flows into the upper primary side chamber 16 and is discharged to the outside through the deposit discharge pipe 30 from the discharge opening 61 together with the deposit 40 in the upper primary side chamber 16.

  Thereby, even if the deposit 40 in the upper primary side chamber 16 does not pass through the narrow through-passage 11 having a large passage resistance from the top to the bottom, the deposit 40 can be reliably and simultaneously discharged from the discharge opening 61 together with the cleaning water W4. The amount of the deposit 40 remaining in the upper primary side chamber 16 can be greatly reduced by sufficiently discharging the membrane module 1 to the outside.

  Further, after supplying the cleaning water W4 from the supply opening 60 to the upper primary chamber 16 as described above, a pressurized gas G2 (an example of fluid) such as pressurized air is supplied from the supply opening 60 to the upper primary chamber 16. And may be discharged from the discharge opening 61. Thereby, even if the cleaning water W4 and the deposit 40 remain in the upper primary side chamber 16, the remaining cleaning water W4 and the deposit 40 together with the pressurized gas G2 pass through the deposit discharge pipe 30 from the discharge opening 61. It is surely discharged to the outside.

Further, since the supply opening 60 is formed on the side surface of the upper primary side chamber 16, when the cleaning water W4 flows into the upper primary side chamber 16 from the supply opening 60, the deposit 40 in the upper primary side chamber 16 is on the side. Thus, the cleaning water W4 is received from the side, and the deposit 40 is easily peeled off from the upper end surface of the membrane element 3.
(Sixth embodiment)
In each of the above-described embodiments, as shown in FIG. 6, after the membrane filtration step 45 is performed, the back pressure cleaning step 46 is performed, and after the back pressure cleaning step 46, the deposit discharging step 47 is performed. In the sixth embodiment described below, as shown in FIG. 12, after the membrane filtration step 45 is performed, the entire deposit discharge step 47 is overlapped with the back pressure cleaning step 46.

  That is, when the back pressure washing step 46 is performed after completion of the membrane filtration step 45, first, as shown in FIG. 4, the second and fourth valves 32, 34 are opened, and the other valves 31, 33, 35, 36 are opened. Is closed, and the backwash water W1 in the backwash water supply pipe 25 is supplied to the membrane element 3 from the treated water outlet 23. Thereby, the backwash water W1 permeates from the outer periphery (secondary side) of the membrane element 3 to the inner side (primary side), flows from the top to the bottom through the through passage 11 and flows into the lower primary side chamber 17, and the raw water flow It is discharged from the inlet 19 to the outside through the backwash water discharge pipe 21 as backwash drainage.

  Thereby, the foreign matter adhering to the inside of the through channel 11 is separated by the flow of the backwash water W1, passes through the raw water inlet 19 from the lower primary side chamber 17 together with the backwash water W1, and is discharged as backwash water as backwash water. The membrane element 3 is discharged to the conduit 21 and subjected to back pressure cleaning.

  In addition, when performing the said back pressure washing | cleaning process 46, backwash water W1 is caused by the pressure drop accompanying the backwash water W1 passing from the outer periphery (secondary side) to the inside (primary side) of the membrane element 3. The gas component dissolved therein may be gasified and entrained in the surface of the membrane element 3 or the backwash water W1 to enter the membrane module 1 and be collected and retained in the upper primary side chamber 16. .

  When the predetermined time t elapses while the back pressure cleaning step 46 is performed, the deposit discharge step 47 is further back pressure cleaned by opening the sixth valve 36 as shown in FIGS. This is duplicated with step 46.

  As a result, the backwash water W1 permeates from the outer periphery (secondary side) of the membrane element 3 to the inner side (primary side), and a part of the backwash water W1 flows from the top to the bottom through the through flow path 11 to enter the lower primary side chamber 17 In the upper primary side chamber 16, the remaining backwash water W1 flows upward through the through-flow passage 11 and is discharged from the raw water inlet 19 through the backwash water discharge pipe 21 as backwash drainage. The deposit 40 in the upper primary chamber 16 and the gas staying in the upper primary chamber 16 are discharged to the outside through the deposit discharge line 30 from the pressurized gas inlet 27 together with the backwash water W1. . As a result, it is possible to shorten the time required to extract the gas staying in the membrane module 1, and the back pressure cleaning step 46 and the deposit discharge step 47 as in the first to fifth embodiments. Compared with the case where it does not overlap, the time which combined the back pressure washing | cleaning process 46 and the deposit discharge process 47 can be shortened. For this reason, the deposit discharge process 47 can be performed every time the back pressure cleaning process 46 is performed.

Thereafter, the sixth valve 36 is closed, and the deposit discharging step 47 is finished. Thereafter, in the back pressure cleaning step 46 (see FIG. 4), by opening the fifth valve 35, the back pressure water G1 (pressure air) in the pressure gas supply line 28 is supplied while supplying back water W1. Etc.) is supplied into the upper primary side chamber 16 from the pressurized gas inlet 27, so that the backwash water W1 remaining in the casing 2 is reliably fed into the raw water inlet by the pressurized gas G1 together with the separated foreign matter. 19 is discharged through a backwash water discharge pipe 21. After performing the flushing process for a predetermined time in this way, the back pressure cleaning process 46 is finished.
(Seventh embodiment)
In the sixth embodiment, as shown in FIG. 12, the entire deposit discharging step 47 is performed overlapping with the back pressure cleaning step 46. However, in the seventh embodiment described below, As shown in FIG. 14, a part of the deposit discharge process 47 is overlapped with the back pressure cleaning process 46.

  That is, in the back pressure washing process 46, as shown in FIG. 4, the second and fourth valves 32, 34 are opened, the other valves 31, 33, 35, 36 are closed, and the backwash water supply line 25 is closed. The backwash water W <b> 1 is supplied from the treated water outlet 23 to the membrane element 3. Thereby, the backwash water W1 permeates from the outer periphery (secondary side) of the membrane element 3 to the inner side (primary side), flows from the top to the bottom through the through passage 11 and flows into the lower primary side chamber 17, and the raw water flow It is discharged from the inlet 19 to the outside through the backwash water discharge pipe 21 as backwash drainage.

  Thereby, the foreign matter adhering to the inside of the through channel 11 is separated by the flow of the backwash water W1, passes through the raw water inlet 19 from the lower primary side chamber 17 together with the backwash water W1, and is discharged as backwash water as backwash water. The membrane element 3 is discharged to the conduit 21 and subjected to back pressure cleaning.

  In this state, after a predetermined time has elapsed, the fifth valve 35 is further opened, so that the pressurized gas G1 (such as pressurized air) in the pressurized gas supply pipe 28 is pressurized while supplying the backwash water W1. Since the backwashing water W1 remaining in the casing 2 is supplied from the gas inlet 27 into the upper primary side chamber 16, the backwashing water reliably from the raw water inlet 19 by the pressurized gas G1 together with the separated foreign matter. It is discharged through the discharge line 21.

  After performing the flushing process for a predetermined time in this way, the fifth valve 35 is closed, and the sixth valve 36 is further opened as shown in FIGS. 46, the deposit discharging step 47 is repeated. As a result, the backwash water W1 permeates from the outer periphery (secondary side) of the membrane element 3 to the inner side (primary side), and a part of the backwash water W1 flows from the top to the bottom through the through flow path 11 to enter the lower primary side chamber 17 In the upper primary side chamber 16, the remaining backwash water W1 flows upward through the through-flow passage 11 and is discharged from the raw water inlet 19 through the backwash water discharge pipe 21 as backwash drainage. The deposit 40 in the upper primary chamber 16 and the gas staying in the upper primary chamber 16 are discharged to the outside through the deposit discharge line 30 from the pressurized gas inlet 27 together with the backwash water W1. . As a result, it is possible to shorten the time required to extract the gas staying in the membrane module 1, and the back pressure cleaning step 46 and the deposit discharge step 47 as in the first to fifth embodiments. Compared with the case where it does not overlap, the time which combined the back pressure washing | cleaning process 46 and the deposit discharge process 47 can be shortened. For this reason, the deposit discharge process 47 can be performed every time the back pressure cleaning process 46 is performed.

  After a predetermined time t has elapsed in this state, as shown in FIGS. 5 and 14, the second valve 32 is closed, the back pressure cleaning step 46 is terminated, and only the deposit discharging step 47 is subsequently performed. As a result, the backwash water W1 permeates from the outer periphery of the membrane element 3 to the inside, flows upward through the through passage 11 and flows into the upper primary side chamber 16, and pressurizes together with the deposit 40 in the upper primary side chamber 16. The gas is discharged from the gas inlet 27 through the sediment discharge pipe 30 to the outside.

  In the seventh embodiment, the flushing process which is a part of the back pressure cleaning process 46 is performed. However, the flushing process may not be performed.

  In each of the above embodiments, the membrane element 3 in which the separation membrane layer is formed on the inner peripheral surface of the through channel 11 is shown. However, the separation membrane layer is not separately formed, and the cylindrical porous body itself is the separation membrane. It may fulfill the role of.

  In each of the above embodiments, the cylindrical membrane element 3 is shown, but it may be a prismatic shape (polygon).

DESCRIPTION OF SYMBOLS 1 Membrane module 2 Casing 3 Membrane element 11 Through flow path 16 Upper primary side chamber 17 Lower primary side chamber 40 Deposit 45 Membrane filtration step 46 Back pressure washing step 47 Deposit discharge step 56 Discharge opening 60 Supply opening 61 Discharge opening G2 Pressurized gas (fluid)
W1 Backwash water (backwash fluid)
W2 Raw water (fluid)
W3 treated water (fluid)
W4 Wash water (fluid)

Claims (9)

A membrane element made of a columnar porous body is housed in a casing,
The membrane element has a plurality of through-flow passages penetrating from one end to the other end and having the inner peripheral surface as the primary side, and is provided in the casing so that the through-flow passage is in the vertical direction.
In the upper part of the casing, an upper primary side chamber is formed which is exposed to the upper end portion of the membrane element and communicates with the through flow path.
A membrane module operating method for obtaining treated water by filtering raw water through a membrane element,
A method for operating a membrane module, comprising a deposit discharging step of supplying a fluid into an upper primary chamber and discharging the deposit in the upper primary chamber together with the fluid. 2. The method for operating a membrane module according to claim 1, wherein in the deposit discharging step, the deposit in the upper primary chamber is discharged outside without passing through the through channel of the membrane element. 3. The membrane module according to claim 1, wherein in the deposit discharging step, the fluid is supplied from the secondary side of the membrane module to the upper primary side chamber through the through passage of the membrane element. how to drive. In the lower part of the casing, a lower primary side chamber communicating with the through channel is formed while the lower end of the membrane element is exposed,
The method for operating a membrane module according to claim 1 or 2, wherein in the deposit discharging step, the fluid is supplied from the lower primary side chamber to the upper primary side chamber through the through passage of the membrane element. . In the lower part of the casing, a lower primary side chamber communicating with the through channel is formed while the lower end of the membrane element is exposed,
Having a membrane filtration step and a back pressure washing step,
In the membrane filtration step, raw water is supplied to the lower primary side chamber, permeates from the primary side to the secondary side of the membrane module by the dead end filtration method, and is taken out from the secondary side of the membrane module as treated water,
In the back pressure washing process, the back washing fluid is supplied to the membrane element from the secondary side of the membrane module, passes through the membrane element, and is discharged to the outside from the lower primary side chamber through the through channel. The operation method of the membrane module according to any one of claims 1 to 4. When the membrane filtration step and the back pressure washing step are alternately repeated and a predetermined time has elapsed, the number of times of both the above steps has reached a predetermined number, or the predetermined operating parameter has reached a predetermined value The method of operating a membrane module according to claim 5, wherein a deposit discharging step is performed. All or part of the sediment discharge process is performed in duplicate with the back pressure cleaning process,
When the deposit discharge process is performed overlapping with the back pressure cleaning process, the backwash fluid that has passed through the membrane element from the secondary side of the membrane module is discharged to the outside from the upper primary chamber and the lower primary chamber. The method for operating a membrane module according to claim 5. A membrane module that obtains treated water by filtering raw water through a membrane element,
A membrane element made of a columnar porous body is housed in a casing,
The membrane element has a plurality of through-flow passages penetrating from one end to the other end and having the inner peripheral surface as the primary side, and is provided in the casing so that the through-flow passage is in the vertical direction.
In the upper part of the casing, an upper primary side chamber is formed which is exposed to the upper end portion of the membrane element and communicates with the through flow path.
A membrane module, wherein a discharge opening for discharging deposits together with a fluid to the outside of the upper primary chamber is provided on a side surface of the upper primary chamber. A membrane module that obtains treated water by filtering raw water through a membrane element,
A membrane element made of a columnar porous body is housed in a casing,
The membrane element has a plurality of through-flow passages penetrating from one end to the other end and having the inner peripheral surface as the primary side, and is provided in the casing so that the through-flow passage is in the vertical direction.
In the upper part of the casing, an upper primary side chamber is formed which is exposed to the upper end portion of the membrane element and communicates with the through flow path.
A membrane module, characterized in that a supply opening for supplying a fluid for discharging deposits into the upper primary chamber is provided on a side surface of the upper primary chamber.

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